Bore crown adapted to be used in diamond drilling



March 27, 1962 1, A 3,026,952

BORE CROWN ADAPTED TO BE USED IN DIAMOND DRILLING Filed Sept. 3, 1959 IA VEQ ToR IngvodLd H 3,026,952 BORE CROWN ADAPTED TO BE USED IN DIAMOND DRHLLPLNG lngvald Am, Boliden, Sweden, assignor to Bolidens Gruvaktieboiag, Slrelleftehamn, Sweden, a joint=stocir company limited of Sweden Filed Sept. 3, 1959, Ser. No. 837,835

2 Claims. (ill. l'75-33ll) The present invention relates to a bore crown which is adapted to be used in diamond drilling and comprises a cylindrical tool which is arranged to be rotated for freeing a core by means of diamonds fixed to said crown which core will pass through a central core hole of said crown.

For deep drilling, so-called diamond drilling is used to an ever increasing degree. In such-connection a socalled bore crown is used as a tool which crown is shaped as a cylinder provided with a central hole. This cylinder can be threaded into fixed position in a so-called core pipe which is rotated in turn by means of power from any suitable source, for instance an internal combustion engine or an electrical motor. The bore crown used with the drilling is provided with diamonds which during the drilling operation are pressed against the rock. Said diamonds will wear on the rock in such a way as to form an annular hole within which remains a cylindrical core which is received by the core pipe tightened above the bore crown. In order to provide for a rinsing of the hole drilled a suitable scavenging fluid is supplied, for instance Water, but even air. This scavenging fluid is caused to pass through the core pipe down to the drilling zone and thereafter on the outside of the bore crown and along the walls of the core pipe up to the surface. The purpose of the actual scavenging is to provide for a removal of the finely pulverized material obtained when drilling the annular hole. It has proved, however, that a strong choking up occurs in the core hole of said bore crown in the above drilling operation, whereby the rinsing fluid will not reach the zone of drilling.

The present invention has for its purpose to avoid said choking up and is mainly characterized therein that the wall of the bore crown is traversed by a duct system adapted for the supply of cooling liquid, said duct system leading to the working zone of said tool and communicating with said core hole.

An embodiment of the present invention is shown by way of example in an axial section on the attached drawmg.

Referring now to the drawing the bore crown is generally designated by 1. This crown is tightened by being threaded into a so-called bore pipe 2 which serves as a collecting member for the core formed during the drilling. The cutting edges of the bore crown are designated by 3. The bore crown is traversed by a central hole 4 which is conically shaped and tapers towards the drilling zone proper of the tool. The drilling tool is further provided with a washer 5 having a central hole 8 and arranged in the top of the bore crown, said washer being placed about the inlet openings for the ducts 6 characteristic for the invention, which ducts extend in the longitudinal direction of the bore crown from the end portion which is in contact with the core pipe to that part of the bore crown in which the cutting edges of the bore crown are located. As will be evident from the drawing there is an open space below the washer 5 which, in part, includes an annular passage 7 below the washer 5 which 3,926,952 Patented Mar. 27, 11962 ice passage is throttled as compared with the remainder of the duct system and between the central hole 4 and ducts 6, which passage 7 avoids that coarse particles resulting from the drilling operation will pass into the ducts 6 choking up the passage of rinsing fluid therethrough.

The above ducts 6 are arranged in such a way that they will rinse the cutting edges of the bore crown facilitating their work during the drilling operation. The rinsing fluid is supplied via the core pipe 2 and will thus pass through the actual ducts 6 and the drilling zone 3. Thereafter it will pass along the outside of the outer wall of the bore crown 1 and along the outer wall of the core pipe 2.

The invention is not limited to the embodiment shown and described but may be varied in several ways within the scope of the basic inventive idea.

Having now described the invention, what I claim as new and desire to secure by Letters Patent, is:

1. A diamond drilling crown comprising a cylindrical diamond carrying body having an upper end and a lower end having a working surface, said body having a central, upwardly flaring core hole opening through both ends of said body, the working surface of said body being provided with a plurality of radially disposed grooves for the distribution of a flushing fluid over the working surface of said body, circumferentially spaced ducts extending between and opening through the lower and upper ends of said body to provide for the passage of flushing fluid through said body to said grooves in said working surface, and means providing a narrow passage extending between said flaring core hole at the upper end of said body and the upper ends of said ducts so as to prevent blocking by material ascending through said hole.

2. A diamond drilling crown comprising a cylindrical diamond carrying body having an upper end and a lower end having a working surface, said body having a central, upwardly flaring core hole opening through both ends of said body, the working surface of said body being provided with a plurality of radially disposed grooves for the distribution of a flushing fluid over the working surface of said body, circumferentially spaced ducts extending between and opening through the upper and lower ends of said body to provide passage ways for the passage of flushing fluid to said grooves in said working surface, means overlying the upper end of said body in upwardly spaced relation the upper ends of the ducts and being spaced from that portion of said body intermediate said core hole and said ducts a distance less than the minimum cross-sectional dimension of said ducts to form a narrow annular passage communicating the upper ends of the ducts with the core hole to prevent blocking of the ducts by material ascending through said core hole, said means having a central opening generally aligned with said core hole and an outer portion resting on an upwardly projecting outer extension of said body.

References Cited in the file of this patent UNITED STATES PATENTS 817,296 Beeson Apr. 10, 1906 2,021,184 Hill Nov. 19, 1935 2,159,249 Brantly May 23, 1939 2,330,155 Stokes Sept. 21, 1943 2,668,037 Stokes Feb. 2, 1954 2,854,219 MacNeil Sept. 30, 1958 FOREIGN PATENTS 694,925 Great Britain July 29, 1953 

